Kirsten Walsh writes…
Last week I competed in the Otago University Three-Minute Thesis Competition. I had to explain my PhD thesis in no longer than three minutes. It was challenging indeed, in such a short length of time, to describe my research, communicate its significance and impart my enthusiasm for it – while pitching it at the level of an intelligent non-expert. Fortunately, I had great material to work with. There are so many interesting stories about Newton! Unfortunately, it’s often difficult to figure out which stories are true.
I opted to begin with the ‘approximately true’ story of Newton’s anni mirabilis, or miraculous years. The general thrust of the story is true, even if some of the particulars are false: the plague years mark a significant turning point in Newton’s scientific work. As Whiteside pointed out over forty years ago, we may
- “salute this first creative outburst – whether or not contained in one single marvelous year – of a man who twenty years afterwards was to construct a scientific Weltanschauung which is, in its essentials, still ours.”
So, with apologies to those of you with ‘historically sensitive’ ears, here is my script for the three-minute thesis competition:
It’s 1665. Cambridge has been struck by Plague, and Newton has been sent home from University. Summer is stretching out before him. Nice! What will he do on his extended summer holiday? Well, he did what I imagine most Scarifies* do on their summer holidays: he invented calculus, discovered the composition of light, and (after watching an apple fall from a tree) conceived the laws of universal gravitation… Okay, so perhaps Newton wasn’t quite your typical undergraduate student. The story about the apple is controversial, but everyone agrees about the discoveries. Scholars have called those years the ‘years of miracles’.
Why were they ‘miraculous’? Well, these were revolutionary discoveries – and there were so many of them. They provided the basic material for Newton’s Principia, and his Opticks. Enough material for a lifetime of publications! And real publications. Not just those ‘puff pieces’ that fill our journals nowadays. All in just 2 years!
Furthermore, these discoveries seemed to come out of nowhere. Newton was able to invent, discover and conceive things no one else could, because seemingly he had invented an entirely new scientific method. He had come up with a whole new way of mathematising physics, and claimed to have achieved mathematical certainty! Philosophers and scientists tried to emulate his method. But no one was as successful as Newton. Whatever Newton was doing, he was doing it right. But what was he doing?
This is the central question of my PhD, and it’s a question that dominates discussions of scientific method even now, 300 years later. But scholars still barely understand what Newton’s method was. Did Newton really think his scientific theories were as certain as mathematical proofs? Why did he think his theory of gravity was true, when he couldn’t even say for certain what gravity is? And, at the centre of it all, the question that’s been keeping me up at nights (as it has kept up generations of Newton-scholars before me): what did Newton mean when he wrote that enigmatic sentence at the end of Principia: ‘Hypotheses non fingo’; ‘I do not feign hypotheses’?
I do not feign hypotheses. What an odd thing to say. What does it even mean? ‘I haven’t invented these hypotheses’? ‘I didn’t prove them’? This sentence lies at the heart of my thesis. Unlike other Newton scholars, I think it describes a crucial aspect of Newton’s method. What it tells us is that Newton made a distinction. On the one hand, theories: mathematical, certain, experimentally confirmed. On the other hand, hypotheses: non-mathematical, uncertain, non-experimental, and speculative. This distinction is a crucial feature of Newton’s spectacularly successful scientific method. And I think it’s this distinction that explains Newton’s years of miracles.
The idea of anni mirabiles seems closely-related to the notion of a scientific revolution, which has been much discussed since Kuhn published The Structure of Scientific Revolutions in 1962. Philosophers of science disagree philosophically over the importance of revolutions to science, and historically over the occurrence of any genuine scientific revolutions. However, it is interesting to note that historians have recognised several anni mirabiles in the history of science. For example, 1543, the year that Vesalius published De Humani Corporis Fabrica and Copernicus published De Revolutionibus Orbium Coelestium. And 1905, the year that Einstein published his three ground-breaking papers in the Annalen der Physik. What role have these anni mirabiles played in the history of science? What do they tell us about scientific progress? Norwood R Hanson once said:
- “It is possible both to be driven by intuition and at the same time to reason carefully. Most scientific discoveries, indeed, result from just such an intertwining of headwork and guesswork.”
What do you think?
*Otago Undergraduate Students